Testing GWT RPC services

You may know that testing with GWTTestCase are very slow. And there are many posts about testing GWT applications without using GWTTestCase.

However, it is still hard to test our RPC remote services. That is the reason I decided to develop SyncProxy which can run directly from pure Java (non JSNI) code.

For example, we have an helloApp application and we want to test our GreetingService

@RemoteServiceRelativePath("greet")
public interface GreetingService extends RemoteService {
  String greetServer(String name);
}

Assume the server side of application is running (whether in DevMode or deployed to an web server) and the servlet URL is configured at http://localhost/helloApp/greet

The test case

public class GreetingServiceTest extends TestCase{
  private static GreetingService rpcService =
    SyncProxy.newProxyInstance(GreetingService.class,
          "http://localhost/helloApp", "greet");

  public void testGreeting() {
    String result = rpcService.greetServer("SyncProxy");
    assertTrue((result != null) && (result.startsWith("Hello, SyncProxy")))
  }
}

SyncProxy.newProxyInstance() method requires a service interface class, a base URL and a relative servlet path.

SyncProxy will search for RPC policy files (*.gwt.rpc files) to determine appropriate policy name for the service interface. Thus, we copy gwt.rpc files from war/helloApp directory to our test case classpath.

SyncProxy.newProxyInstance() will return a new proxy instance which implements our GreetingService interface.

By design SyncProxy is synchronous, e.g it invoke the remote service and wait for the result. However, our GWT logic code invokes the remote service asynchronously. SyncProxy can simulate the ‘Async’ mode too.

GreetingServiceAsync rpcServiceAsync =
SyncProxy.newProxyInstance(GreetingServiceAsync.class,
          "http://localhost/helloApp", "greet");

The code is almost the same as section above, except we use the Async version of the remote service interface.

rpcService.greetServer("SyncProxy", new AsyncCallback<String>(){
  public void onFailure(Throwable caught) {
    ...
  }
  public void onSuccess(String result) {
    ...
  }
});

Get SyncProxy (with source code) at our Downloads page

SyncProxy includes test suite (see the Java source file com.gdevelop.gwt.syncrpc.test.RPCSyncSuite) to test against the standard GTW RPC test.

Updated on 2010/03/03: Version 0.1.1 is released with cookie supports

Updated on 2010/03/13: New post Invoke GWT RPC services deployed on Google App Engine.